Despite improvements in management of acute allograft rejection and 1 year survival of allografts, many organs succumb sooner or later to chronic allograft rejection/injury. Important contributor to this process is chronic vascular rejection in any organ, and bronchilitis obliterans in transplanted lungs. In the present program project we propose that the abnormal deposits of extracellular matrix seen in bronchioles with obliterative bronchiolitis and arteries with chronic allograft vasculopathy obey to an abnormal humoral and cellular immunity to the generation of excess col(V) al homotrimers in the extracellular matrix. The goal of the Core C, Pathology Core is to provide the histopathology and immunopathology analysis in support of the three proposed projects of the program. Specifically, animal models and human tissues derived from the projects will be analyzed for histomorphologic changes, immunohistochemistry and specialized tissue analysis techniques to characterize extracellular matrix components, and cellular, humoral and soluble mediators of the immune response related to autoimmunity to collagen V in chronic allograft injury. The Core will ensure the appropriate flow of human and animal model tissue between the different institution and laboratories of the program as well as the adequate use of resources pertinent to the Core. The Core has proposed 5 main aims to aid the program projects at different steps, including diagnostic histopathology of biopsies, immunohistochemistry of animal models and human tissue, laser capture microdissection, morphometric analysis and detection of cytokines in human and animal samples. The Core leader. Dr. Jose R. Torrealba, a pathologist specialized in organ transplantation, will provide all the diagnostic histopathology and coordinate the activities of the Core. Numerous manuscripts, including recent publications with the program project Pis, demonstrate the collaboration capabilities and resources of the Core.